ZHCSKD9 October 2019 ADS1235-Q1
PRODUCTION DATA.
It is important to evaluate circumstances when an input signal is present with the ADC, both powered and unpowered. When the input signal exceeds the power-supply voltage, it is possible to backdrive the analog power-supply voltage with the input signal through a conduction path of the internal ESD diodes. Backdriving the ADC power supply can also occur when the power-supply is on. The backdriven current path is illustrated in Figure 88. Depending on how the power supply responds during a backdriven condition, it is possible to exceed the maximum rated ADC supply voltage. The ADC voltage must not be exceeded at all times. One solution is to clamp the analog supply to safe voltage using an external zener diode.